Identification from bite marks in a sexual assault case involving multiple assailants by DNA profiling

  • Sarabjeet Singh Ph.D., Senior Forensic Chemical Examiner/Asstt.Director, DNA/ BIOLOGY Division, Forensic Science Service, Govt of National Capital Territory, New Delhi.
  • Rajinderpal Singh Indian Armed Forces (AD Corps), BBS, Memorial Charitable Hospital, Urmar Tanda
  • Rakesh K. Gorea Faculty member, College of Medicine, Prince Sattam bin Abdul Aziz University, Al Kharj -Saudi Arabia.
  • Yashmeen Sharma Department of DNA Fingerprinting, Forensic Science Laboratory, Govt. of National Capital Territory, New Delhi.
Keywords: Forensic Science, Bite marks, Saliva, STRs, DNA Profiling, Rape cases.


Bite mark evidence is often introduced as being close to DNA in terms of accuracy. Bite marks are generally found at the scene of violent crime murders, sexual assaults and are an extremely difficult process to collect the bite marks/saliva sample very lightly, otherwise, only victim profile will be generated. On examination of victim's right breast, a patterned injury was discovered and determined to be from adult male’s teeth. Evidence was collected by the forensic doctor according to established techniques including recovery of saliva from the bite mark area despite the body. DNA analysis by PCR using polymorphic STR markers revealed a DNA profile of mixed origin. With the advent of more sensitive typing methodologies, fingernails clipping for foreign DNA, as well as swabs collected from the area on the victim's body (kissed, licked, genital area, bitten area from breast and lips), are analyzed. In addition, finger swabs for nail scrapping in the case of digital penetration could also be collected from the suspect for DNA analysis, findings new repeats of DNA. Generally, Victim’s DNA profile, a genotype contribution from the perpetrator was identified as a minor component. Thus the DNA typing results from the bite mark correlated with the DNA typing results obtained from other biological trace evidence identified from the victim's genital samples. The bite mark and the DNA evidence were used to screen suspects and played an important role in obtaining resolution of this case. In this study DNA profiled from the breast swab from bitten area, finger swabs, and a control sample of assailants were obtained for all STR loci using AmpflSTR Identifier kit.